>>1959908
Just make the USMC match the irl one. Good quality infantry with upgrade packages, decent logistical/trans helis and limited attack helis, good fixed wing naval aviation and drones, limited long range precision missile artillery but with no armor and just light amphibious vehicles. Your heaviest stuff would be AAVs and ACVs. It would be a deck focused around strong mobile infantry and recon spotting for powerful but limited precision aviation and indirect fire.

Different than the US airborne that would have strategic air mobility and heavier attack aviation options.